Whilst the sterile packaging of liquids can be achieved using many means, those containers that allow the liquids to be dispensed through valves face the problem of the liquid content maintaining sterility and preventing oxygen ingress, especially during dispensing. In dispensing sterile fluids from containers it is important to prevent any back flow of contamination into the container during and after the dispensing operation has been carried out. This is particularly important where the container has an extended period of use. If a container of a sterile fluid has a one-time use and is not intended to be dispensed over an extended period of time, the problem of contaminants flowing into the container usually does not exist. However where a container is used for some time, contamination in the form of materials originating from outside of the valve assembly and container may include microorganisms, atmospheric gases, moisture, dust and the like. If the sterile fluid is contaminated it can affect the quality, potency and even safety of the product.
The present invention is directed to a valve assembly for use in discharging a liquid from a container and for preventing any flow of contaminants through the valve assembly into the container. The valve assembly includes a valve body with an elastomeric sheath within the valve that when expanded provides for a liquid flow path for dispensing the liquid from the container.
Maintaining the contents sterile and free of oxygen ingress during dispensing is a challenge for most designers. U.S. Pat. No. 4,846,810 describes a valve assembly that claims to prevent backflow of contaminants including microorganisms and air during and following the dispensing of fluids.
This patent describes a concept of allowing pressurized liquid to pass through a valve body containing channels that make contact with an elastomeric membrane at the surface before entering another channel. This port as it is referred to in the patent, in the absence of liquid pressure, remains tightly pressed against the valve body (elastomeric force), effectively preventing fluid, contaminants or organisms from moving beyond this point. It is claimed that such a valve has been tested and remains aseptic during use for dispensing of liquid. The invention does however have several limitations. These are:                1. That pressure higher than gravity is required to dispense from this valve rendering the invention suitable only for pressurized collapsible containers and not so for gravity dispensed liquids stored within a collapsible bag or a rigid container.        2. The invention although suitable for aseptic dispensing, does not describe any suitable method of opening and shutting the valve in order to maintain sterility of the liquid during valve use. Maintaining sterility requires a chain of mechanisms to be useful such as fluid release control.        3. The valve does not mention the use of a breather for it to be adoptable to more rigid containers such as Poly Ethylene Terephthalate (PET) bottles.        